Nowadays, automobile manufacturers are developing electric vehicles to reduce exhaust emissions from vehicles. In an electric vehicle, when the state of charge becomes low in a battery, which is the power source of the vehicle, a household outlet or charging stand must be used to charge the battery.
Japanese Laid-Open Patent Publication No. 9-161898 describes a system for charging an electric vehicle that can easily be used by a user. In the prior art charging system, the vehicle includes an inlet, or connector receptacle, to which a charging connector (charging coupler) is connected. The charging connector is plugged to, for example, a household commercial power grid. For example, when the user goes home, the user connects the charging connector to the inlet of the parked vehicle to charge the vehicle battery with commercial power.
Quick charging techniques for electric vehicle batteries have been developed. However, in comparison with when filling a gasoline vehicle with gasoline, battery charging requires a longer time. Further, households, in particular, are generally not equipped with quick charging equipment. When connecting a charging connector, which is plugged to a household outlet, to the inlet of the vehicle to charge the battery at home, the vehicle is often left unattended. In such a case, for example, someone may remove the charging connector from the vehicle that is being charged and connect the charging connector to the inlet of another vehicle to steal electricity. Further, the charging connector itself may be stolen.
Accordingly, there is a demand for a technique that prevents unauthorized removal of the charging connector from the inlet (connector receptacle) of the vehicle.